William Callahan

William Callahan may refer to:


 * William A. Callahan, Canadian political scientist
 * William F. Callahan (1891–1964), chairman of the Massachusetts Turnpike Authority
 * Callahan Tunnel or William F. Callahan Tunnel, a Boston Harbor tunnel
 * William P. Callahan (born 1950), American Roman Catholic bishop
 * William R. Callahan (state representative) (1925–1976), Massachusetts state representative
 * William R. Callahan (priest) (1931–2010), American Roman Catholic priest
 * William Roger Callahan (1931–2022), journalist and politician in Newfoundland, Canada
 * William J. Callahan, Deputy Director of the United States Secret Service

Bill Callahan may refer to:
 * Bill Callahan (American football) (born 1956), American football coach
 * Bill Callahan (defensive back) (born 1964), American football player
 * Bill Callahan (musician) (born 1966), American singer-songwriter
 * Bill Callahan (TV producer), former producer and writer for Scrubs